Natural Spotlight

You can already tell the Master Sword is significant because of this.

In a nutshell, this is using sunlight as though it was a stage spotlight.

Spotlights in theater are often used to highlight a specific thing the play wants the audience to focus on. Thus the other lights are turned off so only what's in the spotlight can be seen.

In media that isn't on stage, even animated media, that isn't an option outside of stylistic works. Other ways have to be found to highlight things. This trope is when light streaming through things, like through windows or tree branches, is used to highlight something relevant. Heck, sometimes there doesn't even have to be something making the sunlight act like that. It just makes the slits on its own.

Usually it's something key to the plot, often of a supernatural nature. The latter sort of justifies this trope, but it's not the only form this trope takes.

Quite common in some western religious artwork.

Note this can only be when it's used as a substitute for a spotlight. If sunlight is actually used in the story to highlight something, like killing Dracula or finding the location of the Ark of the Covenant, it's not this trope.

A Sub-Trope of Dramatic Spotlight.

Compare Rule of Perception, Rule of Symbolism, Emerging From the Shadows.

Examples of Natural Spotlight include:

Anime and Manga

The opening of the 2003 anime adaptation of Fullmetal Alchemist has this at the end coming through the roof of a building with Ed holding his hands up to the light.
In D.Gray-man, "Old Man of the Soil and a Lonely Night's Aria", a spotlight of moonlight shines down on Guzol and Lala in their underground hideout at the moment that the Exorcists find them.
In the Fate Stay Night Anime, Archer appears to summon a natural spotlight (Probably the Moon, although it's odd considering the angle changes) this before he uses Unlimited Blade Works.

Film

Done in exactly the same way in Disney's adaptation of The Sword in the Stone.
Lampshaded in The Blues Brothers. "Do you see the light?"
The iconic scene in the introduction to The Lion King.
A few scenes in The Lord of the Rings, like Balin's tomb.
- Balin's tomb was described like this even in the original novel, explained by ingenious light channels carved by the dwarves in the mountainside. On the other hand, the one lighting Gollum's cave in the prologue comes off as highly improbable, considering its depth and the fact that Gollum can't stand daylight.
In The Addams Family movies, Morticia's face always has a light on it. It is rather obvious and jarring.
Another lit face is Anya's, in the Anastasia movie. The eyes are the ones in focus, which makes one wonder whether or not she notices; most people would certainly be blinded by such thing.
The Thief and the Cobbler: There's a subtle one when Tack the Cobbler is seen the first time, shining on him. It's probably used to signify his pure nature. Particularly Egregious as is seems to come through the ceiling.
In Serenity, Mal's speech to his crew before the final action sequence is lit with copious amounts of light directed at him by overhead windows. In the commentary, Joss notes that on the one hand, this is vaguely believable, but still exists solely because it was awesome.
Snow White's glass coffin at the end of Snow White and The Seven Dwarfs.
Sleeping Beauty: Aurora asleep in the tower.

Literature

In the most recent book of the Wheel of Time series, main character Rand gets one of these shining on him during a key character moment. Possibly justified by the fact that his ta'veren nature warps probability (Its Complicated) and the combination of his being a Fisher King and slowly growing more and more insane has resulted in a continent-wide pattern of overcast weather that only starts to break when he begins to get his screwed-up little head back together.

Video Games

The Master Sword in The Legend of Zelda series is often shown this way.
In Metroid Prime there are a few places where Chozo Statues are resting, the ceiling is cracked and sunlight gets through. (And yet on the "Overworld", it's constantly raining.) The sunlight may not be directly on the statue, but it's close enough to give that entire room that effect.
- Metroid Prime 3: Corruption has a similar statue bathed in sunlight hidden in the depths of Skytown.
On Ilos in Mass Effect, the VI Vigil is in a small room, where a shaft of light shines down on it.

Western Animation

Used both straight and parodied in The Simpsons.
This occurs in the Bugs Bunny short What's Opera, Doc?. After Elmer Fudd's character discovers that "Brunnhilda" is actually Bugs, he summons lightning bolts to "Kill the wabbit!". When Elmer goes to see what happened to Bugs, the area is dark and a shaft of sunlight shines down to reveal Bugs' lifeless body.
During the song "Hellfire" in Disney's The Hunchback of Notre Dame, this happens with moonlight through windows a couple of times.

Real Life

This actually happened to Abraham Lincoln during the Gettysburg Address.